1. Field of the Invention
This invention relates to a tape player, in particular to the locking mechanism for locking a part, which is required to have a plurality of locking positions, such as locking of the head plate for play and for fast forward or reverse drive, by using a single electromagnetic plunger, and to a key-off mechanism causing to return automatically the tape brake to the stop state, when the power source is switched off in any mode state.
2. Description of the Prior Art
Recently, automation of tape players has advanced and it has been proposed to use the driving force of a motor or the attractive force of an electromagnetic solenoid actuated plunger, for these automatic operations. Among them, since even with a relatively small capacity motor it is possible to obtain a fairly large driving force by using a reduction gear, the driving force of a motor is often utilized for displacement of parts for commuting between different modes. On the other hand, an electromagnetic plunger is often utilized for locking the parts which have reached their predetermined position by using a motor, because its work is done instantaneously and its control is easy.
In general, a tape player has the modes and functions utilized such as stop, play, fast forward drive, reverse, channel change and pause, and if all of these operations are automated, an exclusive driving system and locking mechanism is necessary for each of these operations except for stop. Therefore it has been attempted to make a tape player smaller and simpler by making the driving system and locking mechanism have a plurality of functions.
From this point of view the applicants have already proposed a following tape player.
This mechanism is provided with two cam gears which are coupled with a motor and two mode plates driven by each of the cam gears, and when the locking of one of the cam gears is released and a mode plate is moved by the rotation of the cam gear, the fast forward drive mode or the reverse mode is established. On the other hand, when the locking of both the cam gears is released and both the mode plates are moved, the play mode is established. In this mechanism, when either one of the mode plates is moved, the head plate advances so that the head is pressed against the tape (at the play mode) or brought in contact the tape (at the fast forward drive mode) and at the same time in the play mode a pinch roller coupled with the head plate is pressed against a capstan shaft or an idler is pressed against the reel base of the take-up side. In addition, in the fast forward drive and the reverse mode, by displacement of either one of the mode plates a change plate coupled with it is moved toward right or left and presses the idler for the fast forward drive and the reverse drive to the idler of the forward or reverse side. During the continuation of the play or fast forward drive or reverse mode, the return of the head plate, etc. to the stop position is prevented by locking the cam gear in the course of its rotation by means of one of the electromagnetic plungers and by locking the mode plate at its advanced position.
Certainly, since, in a tape player as described above, three modes, i.e. play, fast forward drive and reverse, are realized by two systems, each of them consisting of a driving system and a locking mechanism, it can contribute considerably to miniaturization and simplification of the mechanism of the tape player. However, in order that a tape player can be made still smaller and simpler, the following problematical points are confronted.
That is, in the mechanism described above, since the electromagnetic plungers of the fast forward drive side and that of the reverse side lock the respective one of the mode plates, at the play mode two mode plates, both of which are at their advanced position, are locked simultaneously by the two electromagnetic plungers. As the result, for the operations effected in the play mode, such as program change, pause, etc. these two electromagnetic plungers cannot be used. Consequently, the domain of utilization of the two electromagnetic plungers is considerably limited and they can respond only to three modes, play, fast forward drive and reverse. For this reason, for such operations as program change, pause, etc., the tape player should be provided with another locking mechanism using separate electromagnetic plungers, which prevents the miniaturization of the player and also gives rise to the drawback of complicating the control system.
Moreover, for a tape player mounted in a car, such as a car stereo, etc., the interruption of the power source during the operation of the tape player due to removal of the car key, so-called key-off is often done. In the tape players mentioned above, when a key-off is done at the stop position, since the press state between the pinch roller and the capstan shaft is released, no problem is encountered. However, when the power source is switched off at the working state or in the course of an operation change, the motor ceases to rotate in a state where the cam gear and the driving gear remain engaged, and the cam gear stops in the course of its movement. Being pressed by the cam gear, the mode plate stops also in the course of a movement and it becomes impossible to eject the cassette, or the head plate remains at its advanced position, what gives rise to an inconvenience that the press state of the pinch roller or the idler coupled with it is not released. Further, even if the locking of the driving gear and the cam gear is released, there is a risk that the cam gear is prevented from rotating by the returning force of the head plate, etc. transmitted through one of the mode plates, the mode plate stops there, and its press state is not released.
In this case, the pinch roller and the idler constituting the press mechanism remain to be pressed, which gives rise to wow deficiencies due to rotation fluctuation produced by deformation of the gum ring of the pinch roller or the idler. Furthermore, when the press mechanism is removal at its working position, this produces a drawback that removal of the tape becomes impossible.